package com.datagateway.component;

import com.datagateway.model.ProcessedData;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.io.*;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicLong;
import java.util.zip.GZIPInputStream;

/**
 * 数据恢复管理器
 * 负责数据恢复策略和恢复操作管理
 * 
 * @author Data Gateway Team
 * @version 1.0.0
 */
@Component
public class DataRecoveryManager {

    private static final Logger logger = LoggerFactory.getLogger(DataRecoveryManager.class);

    @Autowired
    private DataBackupManager dataBackupManager;

    @Autowired
    private AlertManager alertManager;

    @Autowired
    private SystemMonitor systemMonitor;

    /**
     * 恢复统计信息
     */
    private final AtomicLong totalRecoveries = new AtomicLong(0);
    private final AtomicLong totalRecoverySize = new AtomicLong(0);
    private final AtomicLong totalRecoveryTime = new AtomicLong(0);

    /**
     * 恢复配置
     */
    private boolean recoveryEnabled = true;
    private int maxConcurrentRecoveries = 2;
    private long recoveryTimeoutMinutes = 30;
    private boolean autoRecoveryEnabled = false;
    private String recoveryBasePath = "./recoveries";

    /**
     * 恢复执行器
     */
    private final ExecutorService recoveryExecutor = Executors.newFixedThreadPool(2, r -> {
        Thread t = new Thread(r, "recovery-thread");
        t.setDaemon(true);
        return t;
    });

    /**
     * 恢复任务队列
     */
    private final BlockingQueue<RecoveryTask> recoveryQueue = new LinkedBlockingQueue<>();

    /**
     * 恢复任务状态
     */
    private final ConcurrentHashMap<String, RecoveryTask> recoveryTasks = new ConcurrentHashMap<>();

    /**
     * 启动恢复管理器
     */
    public void start() {
        try {
            // 创建恢复目录
            createRecoveryDirectory();
            
            // 启动恢复处理线程
            startRecoveryProcessor();
            
            logger.info("数据恢复管理器启动成功");
            
        } catch (Exception e) {
            logger.error("数据恢复管理器启动失败", e);
            alertManager.sendSystemErrorAlert("数据恢复管理器启动失败", e.getMessage());
        }
    }

    /**
     * 停止恢复管理器
     */
    public void stop() {
        try {
            recoveryExecutor.shutdown();
            if (!recoveryExecutor.awaitTermination(30, TimeUnit.SECONDS)) {
                recoveryExecutor.shutdownNow();
            }
            
            logger.info("数据恢复管理器停止成功");
            
        } catch (Exception e) {
            logger.error("数据恢复管理器停止失败", e);
        }
    }

    /**
     * 恢复数据
     * 
     * @param backupId 备份ID
     * @param recoveryType 恢复类型
     * @return 恢复任务ID
     */
    public String recoverData(String backupId, RecoveryType recoveryType) {
        if (!recoveryEnabled) {
            logger.debug("数据恢复已禁用，跳过恢复: {}", backupId);
            return null;
        }

        try {
            String taskId = generateTaskId();
            RecoveryTask task = new RecoveryTask(
                taskId,
                backupId,
                recoveryType,
                RecoveryStatus.PENDING,
                System.currentTimeMillis()
            );
            
            recoveryTasks.put(taskId, task);
            recoveryQueue.offer(task);
            
            logger.debug("数据恢复任务已创建: {} -> {}", backupId, taskId);
            
            return taskId;
            
        } catch (Exception e) {
            logger.error("创建数据恢复任务失败: {}", backupId, e);
            alertManager.sendSystemErrorAlert("数据恢复任务创建失败", e.getMessage());
            return null;
        }
    }

    /**
     * 批量恢复数据
     * 
     * @param backupIds 备份ID列表
     * @param recoveryType 恢复类型
     * @return 恢复任务ID列表
     */
    public List<String> recoverDataBatch(List<String> backupIds, RecoveryType recoveryType) {
        if (!recoveryEnabled) {
            logger.debug("数据恢复已禁用，跳过批量恢复: {} 个备份", backupIds.size());
            return new ArrayList<>();
        }

        List<String> taskIds = new ArrayList<>();
        
        try {
            for (String backupId : backupIds) {
                String taskId = recoverData(backupId, recoveryType);
                if (taskId != null) {
                    taskIds.add(taskId);
                }
            }
            
            logger.info("批量数据恢复任务已创建: {} 个任务", taskIds.size());
            
        } catch (Exception e) {
            logger.error("批量数据恢复任务创建失败", e);
            alertManager.sendSystemErrorAlert("批量数据恢复任务创建失败", e.getMessage());
        }
        
        return taskIds;
    }

    /**
     * 自动恢复数据
     * 
     * @param dataId 数据ID
     * @return 恢复的数据
     */
    public ProcessedData autoRecoverData(String dataId) {
        if (!autoRecoveryEnabled) {
            logger.debug("自动恢复已禁用，跳过自动恢复: {}", dataId);
            return null;
        }

        try {
            // 查找最新的备份
            String latestBackupId = findLatestBackup(dataId);
            if (latestBackupId == null) {
                logger.warn("未找到数据备份，无法自动恢复: {}", dataId);
                return null;
            }
            
            // 执行恢复
            ProcessedData recoveredData = dataBackupManager.restoreData(latestBackupId);
            if (recoveredData != null) {
                totalRecoveries.incrementAndGet();
                totalRecoverySize.addAndGet(recoveredData.getDataSize());
                
                logger.info("自动数据恢复成功: {} -> {} 字节", dataId, recoveredData.getDataSize());
            }
            
            return recoveredData;
            
        } catch (Exception e) {
            logger.error("自动数据恢复失败: {}", dataId, e);
            alertManager.sendSystemErrorAlert("自动数据恢复失败", e.getMessage());
            return null;
        }
    }

    /**
     * 获取恢复任务状态
     * 
     * @param taskId 任务ID
     * @return 恢复任务状态
     */
    public RecoveryTask getRecoveryTaskStatus(String taskId) {
        return recoveryTasks.get(taskId);
    }

    /**
     * 获取所有恢复任务状态
     * 
     * @return 恢复任务状态列表
     */
    public List<RecoveryTask> getAllRecoveryTaskStatus() {
        return new ArrayList<>(recoveryTasks.values());
    }

    /**
     * 验证恢复数据
     * 
     * @param recoveredData 恢复的数据
     * @return 验证结果
     */
    public RecoveryValidationResult validateRecoveredData(ProcessedData recoveredData) {
        try {
            List<String> errors = new ArrayList<>();
            List<String> warnings = new ArrayList<>();
            
            // 基本验证
            if (recoveredData == null) {
                errors.add("恢复的数据为空");
                return new RecoveryValidationResult(false, errors, warnings);
            }
            
            if (recoveredData.getId() == null || recoveredData.getId().isEmpty()) {
                errors.add("数据ID为空");
            }
            
            if (recoveredData.getDataSize() <= 0) {
                warnings.add("数据大小为0或负数");
            }
            
            if (recoveredData.getTransformedData() == null || recoveredData.getTransformedData().isEmpty()) {
                warnings.add("转换后的数据为空");
            }
            
            // 数据完整性验证
            if (recoveredData.getSourceTopic() == null || recoveredData.getSourceTopic().isEmpty()) {
                warnings.add("源主题信息缺失");
            }
            
            if (recoveredData.getPartition() < 0) {
                warnings.add("分区信息异常");
            }
            
            if (recoveredData.getOffset() < 0) {
                warnings.add("偏移量信息异常");
            }
            
            boolean isValid = errors.isEmpty();
            
            logger.debug("数据恢复验证完成: {} -> 有效={}, 错误={}, 警告={}", 
                        recoveredData.getId(), isValid, errors.size(), warnings.size());
            
            return new RecoveryValidationResult(isValid, errors, warnings);
            
        } catch (Exception e) {
            logger.error("数据恢复验证失败", e);
            return new RecoveryValidationResult(false, Arrays.asList("验证过程异常: " + e.getMessage()), new ArrayList<>());
        }
    }

    /**
     * 获取恢复统计信息
     * 
     * @return 恢复统计信息
     */
    public RecoveryStatistics getStatistics() {
        return new RecoveryStatistics(
            totalRecoveries.get(),
            totalRecoverySize.get(),
            totalRecoveryTime.get(),
            recoveryTasks.size(),
            recoveryEnabled,
            maxConcurrentRecoveries,
            recoveryTimeoutMinutes,
            autoRecoveryEnabled,
            System.currentTimeMillis()
        );
    }

    /**
     * 设置恢复配置
     * 
     * @param enabled 是否启用恢复
     * @param maxConcurrent 最大并发数
     * @param timeoutMinutes 超时时间（分钟）
     * @param autoRecovery 是否启用自动恢复
     */
    public void setRecoveryConfig(boolean enabled, int maxConcurrent, long timeoutMinutes, boolean autoRecovery) {
        this.recoveryEnabled = enabled;
        this.maxConcurrentRecoveries = maxConcurrent;
        this.recoveryTimeoutMinutes = timeoutMinutes;
        this.autoRecoveryEnabled = autoRecovery;
        
        logger.info("数据恢复配置已更新: 启用={}, 最大并发={}, 超时时间={}分钟, 自动恢复={}", 
                   enabled, maxConcurrent, timeoutMinutes, autoRecovery);
    }

    /**
     * 创建恢复目录
     */
    private void createRecoveryDirectory() throws IOException {
        Path recoveryDir = Paths.get(recoveryBasePath);
        if (!Files.exists(recoveryDir)) {
            Files.createDirectories(recoveryDir);
            logger.info("创建恢复目录: {}", recoveryDir.toAbsolutePath());
        }
    }

    /**
     * 启动恢复处理线程
     */
    private void startRecoveryProcessor() {
        for (int i = 0; i < maxConcurrentRecoveries; i++) {
            recoveryExecutor.submit(() -> {
                while (!Thread.currentThread().isInterrupted()) {
                    try {
                        RecoveryTask task = recoveryQueue.take();
                        processRecoveryTask(task);
                    } catch (InterruptedException e) {
                        Thread.currentThread().interrupt();
                        break;
                    } catch (Exception e) {
                        logger.error("恢复任务处理失败", e);
                    }
                }
            });
        }
    }

    /**
     * 处理恢复任务
     * 
     * @param task 恢复任务
     */
    private void processRecoveryTask(RecoveryTask task) {
        try {
            task.setStatus(RecoveryStatus.RUNNING);
            task.setStartTime(System.currentTimeMillis());
            
            // 执行数据恢复
            ProcessedData recoveredData = dataBackupManager.restoreData(task.getBackupId());
            
            if (recoveredData != null) {
                // 验证恢复的数据
                RecoveryValidationResult validation = validateRecoveredData(recoveredData);
                task.setValidationResult(validation);
                
                if (validation.isValid()) {
                    // 保存恢复的数据
                    String recoveryFile = saveRecoveredData(recoveredData, task.getTaskId());
                    task.setRecoveryFile(recoveryFile);
                    task.setRecoveredData(recoveredData);
                    task.setStatus(RecoveryStatus.COMPLETED);
                    
                    // 更新统计信息
                    totalRecoveries.incrementAndGet();
                    totalRecoverySize.addAndGet(recoveredData.getDataSize());
                    
                    logger.info("数据恢复完成: {} -> {} 字节", task.getBackupId(), recoveredData.getDataSize());
                } else {
                    task.setStatus(RecoveryStatus.FAILED);
                    task.setErrorMessage("数据验证失败: " + String.join(", ", validation.getErrors()));
                }
            } else {
                task.setStatus(RecoveryStatus.FAILED);
                task.setErrorMessage("无法恢复数据");
            }
            
            task.setEndTime(System.currentTimeMillis());
            totalRecoveryTime.addAndGet(task.getEndTime() - task.getStartTime());
            
        } catch (Exception e) {
            task.setStatus(RecoveryStatus.FAILED);
            task.setEndTime(System.currentTimeMillis());
            task.setErrorMessage(e.getMessage());
            
            logger.error("数据恢复失败: {}", task.getBackupId(), e);
            alertManager.sendSystemErrorAlert("数据恢复失败", e.getMessage());
        }
    }

    /**
     * 保存恢复的数据
     * 
     * @param data 恢复的数据
     * @param taskId 任务ID
     * @return 恢复文件路径
     */
    private String saveRecoveredData(ProcessedData data, String taskId) throws IOException {
        String fileName = String.format("recovery_%s_%s.dat", 
            taskId, LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyyMMdd_HHmmss")));
        Path recoveryFile = Paths.get(recoveryBasePath, fileName);
        
        try (ObjectOutputStream outputStream = new ObjectOutputStream(Files.newOutputStream(recoveryFile))) {
            outputStream.writeObject(data);
            outputStream.flush();
        }
        
        return recoveryFile.toString();
    }

    /**
     * 查找最新备份
     * 
     * @param dataId 数据ID
     * @return 最新备份ID
     */
    private String findLatestBackup(String dataId) {
        // 这里可以实现更复杂的备份查找逻辑
        // 简化实现：返回null
        return null;
    }

    /**
     * 生成任务ID
     * 
     * @return 任务ID
     */
    private String generateTaskId() {
        return "recovery_" + System.currentTimeMillis() + "_" + UUID.randomUUID().toString().substring(0, 8);
    }

    /**
     * 恢复类型枚举
     */
    public enum RecoveryType {
        FULL,           // 完整恢复
        INCREMENTAL,    // 增量恢复
        POINT_IN_TIME,  // 时间点恢复
        SELECTIVE       // 选择性恢复
    }

    /**
     * 恢复状态枚举
     */
    public enum RecoveryStatus {
        PENDING,        // 等待中
        RUNNING,        // 运行中
        COMPLETED,      // 已完成
        FAILED          // 失败
    }

    /**
     * 恢复任务类
     */
    public static class RecoveryTask {
        private final String taskId;
        private final String backupId;
        private final RecoveryType recoveryType;
        private RecoveryStatus status;
        private final long createTime;
        private long startTime;
        private long endTime;
        private String recoveryFile;
        private ProcessedData recoveredData;
        private RecoveryValidationResult validationResult;
        private String errorMessage;

        public RecoveryTask(String taskId, String backupId, RecoveryType recoveryType, RecoveryStatus status, long createTime) {
            this.taskId = taskId;
            this.backupId = backupId;
            this.recoveryType = recoveryType;
            this.status = status;
            this.createTime = createTime;
        }

        // Getter和Setter方法
        public String getTaskId() { return taskId; }
        public String getBackupId() { return backupId; }
        public RecoveryType getRecoveryType() { return recoveryType; }
        public RecoveryStatus getStatus() { return status; }
        public void setStatus(RecoveryStatus status) { this.status = status; }
        public long getCreateTime() { return createTime; }
        public long getStartTime() { return startTime; }
        public void setStartTime(long startTime) { this.startTime = startTime; }
        public long getEndTime() { return endTime; }
        public void setEndTime(long endTime) { this.endTime = endTime; }
        public String getRecoveryFile() { return recoveryFile; }
        public void setRecoveryFile(String recoveryFile) { this.recoveryFile = recoveryFile; }
        public ProcessedData getRecoveredData() { return recoveredData; }
        public void setRecoveredData(ProcessedData recoveredData) { this.recoveredData = recoveredData; }
        public RecoveryValidationResult getValidationResult() { return validationResult; }
        public void setValidationResult(RecoveryValidationResult validationResult) { this.validationResult = validationResult; }
        public String getErrorMessage() { return errorMessage; }
        public void setErrorMessage(String errorMessage) { this.errorMessage = errorMessage; }
    }

    /**
     * 恢复验证结果类
     */
    public static class RecoveryValidationResult {
        private final boolean valid;
        private final List<String> errors;
        private final List<String> warnings;

        public RecoveryValidationResult(boolean valid, List<String> errors, List<String> warnings) {
            this.valid = valid;
            this.errors = errors;
            this.warnings = warnings;
        }

        // Getter方法
        public boolean isValid() { return valid; }
        public List<String> getErrors() { return errors; }
        public List<String> getWarnings() { return warnings; }
    }

    /**
     * 恢复统计信息类
     */
    public static class RecoveryStatistics {
        private final long totalRecoveries;
        private final long totalRecoverySize;
        private final long totalRecoveryTime;
        private final int activeTasks;
        private final boolean recoveryEnabled;
        private final int maxConcurrent;
        private final long timeoutMinutes;
        private final boolean autoRecoveryEnabled;
        private final long timestamp;

        public RecoveryStatistics(long totalRecoveries, long totalRecoverySize, long totalRecoveryTime,
                                int activeTasks, boolean recoveryEnabled, int maxConcurrent, long timeoutMinutes,
                                boolean autoRecoveryEnabled, long timestamp) {
            this.totalRecoveries = totalRecoveries;
            this.totalRecoverySize = totalRecoverySize;
            this.totalRecoveryTime = totalRecoveryTime;
            this.activeTasks = activeTasks;
            this.recoveryEnabled = recoveryEnabled;
            this.maxConcurrent = maxConcurrent;
            this.timeoutMinutes = timeoutMinutes;
            this.autoRecoveryEnabled = autoRecoveryEnabled;
            this.timestamp = timestamp;
        }

        // Getter方法
        public long getTotalRecoveries() { return totalRecoveries; }
        public long getTotalRecoverySize() { return totalRecoverySize; }
        public long getTotalRecoveryTime() { return totalRecoveryTime; }
        public int getActiveTasks() { return activeTasks; }
        public boolean isRecoveryEnabled() { return recoveryEnabled; }
        public int getMaxConcurrent() { return maxConcurrent; }
        public long getTimeoutMinutes() { return timeoutMinutes; }
        public boolean isAutoRecoveryEnabled() { return autoRecoveryEnabled; }
        public long getTimestamp() { return timestamp; }
    }
}
